diff --git a/src/ol/layer/Heatmap.js b/src/ol/layer/Heatmap.js
index dac335798e..eebebf84db 100644
--- a/src/ol/layer/Heatmap.js
+++ b/src/ol/layer/Heatmap.js
@@ -238,7 +238,7 @@ class Heatmap extends VectorLayer {
           float sqRadius = texCoord.x * texCoord.x + texCoord.y * texCoord.y;
           float value = (1.0 - sqrt(sqRadius)) * u_blurSlope;
           float alpha = smoothstep(0.0, 1.0, value) * v_opacity;
-          gl_FragColor = vec4(1.0, 1.0, 1.0, alpha);
+          gl_FragColor = vec4(alpha, alpha, alpha, alpha);
         }`,
       uniforms: {
         u_size: function() {
diff --git a/src/ol/renderer/webgl/PointsLayer.js b/src/ol/renderer/webgl/PointsLayer.js
index ce40fc4c3e..f486476a21 100644
--- a/src/ol/renderer/webgl/PointsLayer.js
+++ b/src/ol/renderer/webgl/PointsLayer.js
@@ -110,8 +110,7 @@ const FRAGMENT_SHADER = `
  *
  * The following uniform is used for the main texture: `u_texture`.
  *
- * Please note that the main shader output should have premultiplied alpha, otherwise the colors will be blended
- * additively.
+ * Please note that the main shader output should have premultiplied alpha, otherwise visual anomalies may occur.
  *
  * Points are rendered as quads with the following structure:
  *
diff --git a/src/ol/webgl/PostProcessingPass.js b/src/ol/webgl/PostProcessingPass.js
index 1563079605..1405398354 100644
--- a/src/ol/webgl/PostProcessingPass.js
+++ b/src/ol/webgl/PostProcessingPass.js
@@ -28,7 +28,6 @@ const DEFAULT_FRAGMENT_SHADER = `
    
   void main() {
     gl_FragColor = texture2D(u_image, v_texCoord);
-    gl_FragColor.rgb *= gl_FragColor.a;
   }
 `;
 
@@ -59,6 +58,9 @@ const DEFAULT_FRAGMENT_SHADER = `
  * a pixel which is 100% red with an opacity of 50% must have a color of (r=0.5, g=0, b=0, a=0.5).
  * Failing to provide pixel colors with premultiplied alpha will result in render anomalies.
  *
+ * The default post-processing pass does *not* multiply color values with alpha value, it expects color values to be
+ * premultiplied.
+ *
  * Default shaders are shown hereafter:
  *
  * * Vertex shader:
@@ -91,7 +93,6 @@ const DEFAULT_FRAGMENT_SHADER = `
  *
  *   void main() {
  *     gl_FragColor = texture2D(u_image, v_texCoord);
- *     gl_FragColor.rgb *= gl_FragColor.a;
  *   }
  *   ```
  *